Abstract

The Java Persistence API (JPA)is the Java API for the management of persistence and object/relational mapping for Java EE and Java SE environments. The persistence consists of three areas:

the API, defined in the javax.persistence package

the Java Persistence Query Language

object/relational metadata

The purpose of this project proposal is to implement a Connector JPA for BIRT framework, and so able to handle data source from the persistence API. Is so great the importance of the project because JPA is a specification that is being used widely in the development of applications, precisely from the advantages it.

The implementation is to make the JPA ODA driver, extending each one of the interface required in the Data Tools Plataform given in the package org.eclipse.datatools.connectivity.oda.

Finalizing it first part will be an improvement approaching also advanced options in regard to the parameters and also will be implemented JPA ODA IU extensions.

Community proposals

Getting the source

Implementation of JPA ODA plugin

The "Statement" class

The "Statement" class, prepare the result set metadata of the query (containing column name, column type, and entity name that belong), execute the query, and fetches the data rows from the Data Source.

Problems founded developing whit JPA in this class:

1. To get attributes of the entities (field names and field types) found into the query e.g.:

SELECT d.departmentIdentifier, d.name
FROM Department d

Was necessary know the complete path, like “jfabian.model.department.entity.Department”, an option was write this in the query as is possible in hibernate but this idea was discard becouse JPA not allow it.

The solution was getting the name of entity and searches the complete path into “persistence.xml” file, this implemented in “JPAUtil.findEntityOnPersistenceXML(entityName, classNodes)” function.

2. Other aspect to take into consideration are the entity alias, this to retrieve the corresponding column e.g.:

In this query the alias for Department is “d”, and its columns are “departmentIdentifier” and “name”, to retrieve the columns types I need know the entity name (with path complete), and column or field name.

And the functionality should be correct if the column order is not the same to instance of the entities, e.g.:

For this task was implemented “extractColumns(qry)”, that return a “List<List<String>>” containing the entity alias and column name.
Other was “getReturnEntities( String query )”, that return a “List<List<String> >” containing entity name and entity alias.

Work future

A) Yet not support the recognition of alias with “as” like:

SELECT d.name FROM Department as d

B) Yet not support retrieve all columns of the entity (similarity to Selec *from department in JDBC):

SELECT d FROM Department as d

C) When a entity has a member variable to other entity, retrieve its metadata still is not possible:

SELECT d.director.firstName FROM Department d

In this case “director” is an entity “Employee”

D) Yet not distinguish some reserved words like:

SELECT DISTINCT d.name FROM Department d

E) Collection member declaration*

SELECT DISTINCT l.product FROM Order AS o, IN(o.lineItems) l

F) The possibility for retrieve metadata when use aggregate functions *

Video Demo of demostration

In this video we are preparing all necesary for generate the report, like; install BIRT Runtime, deploy the ODA JPA plug-in, create the JPA test project, install the Sample database, configure the report, etc.: